We've noticed a sudden spike of issues for many of our clients who use DSCI phones (now TPX). We reached out to TPX and got confirmation that they're having an issue with their Hosted VoIP servers which are affecting many sites around the Boston area.

They are actively working on getting this fixed, we'll be in touch with them and will let you know if there are any actions that need to be taken in conjunction with getting the issues ironed out.